I find the monthly publications like JEMS, EMS Magazine and Canadian Emergency News enjoyable reads, but of limited utility for further education. Certainly they have good educational articles, but the majority of the publications are more like a trade magazine. Lots of new gear to ogle, some industry issues, but certainly not a peer-reviewed journal. That being said, I subscribe to all three.
I also have a subscription to the peer-reviewed journal Prehospital Emergency Care. This is an excellent publication for gaining a deeper understanding of various conditions and treatment modalities we use. It's a quarterly journal and the subscription is pricey, but I found it worthwhile.
I've also read lots of articles grabbed from Annals of Emergency Medicine, but I can't bring myself to buy another pricey journal just yet.